Ingrid 't Hart

35 Chemoenzyma�c synthesis of DSGb5 2 NMR nomenclature The monosaccharides of glycan DSGb5 have been labeled as shown in Fig. S1. Star�ng from the reducing end of the pentasaccharide core Gb5, these were labeled as Glc-I, Gal-II, Gal-III, GalNAc-IV, Gal-V. The sialosides were named Neu5Ac- VI for the α2,3-linked sialic acid and Neu5Ac-VII for the α2,6-linked sialic acid. Figure S1. Monosaccharide labeling system for DSGb5 Experimental procedures 2,2,2-Trichloroace�midate 2,3,4,6-O-acetyl-α-D-galactopyranoside (9). Compound 9 was synthesized according to previous synthesis. 34 NMRs of the α-anomer of the �tle compound are described below. 1H NMR (400 MHz, CDCl 3 ) δ 8.66 (1H, s, NH), 6.58 (1H, d, J = 3.1 Hz, H-1), 5.55 (1H, d, J = 2.6 Hz, H-4), 5.45 – 5.31 (2H, m, H-3, H-2), 4.43 (1H, t, J = 6.6 Hz, H-5), 4.20 – 4.01 (2H, m, H-6), 2.15 (3H, s, OAc), 2.03 – 1.98 (9H, m, 3x OAc). 13 C NMR (101 MHz, CDCl 3 ) δ 170.2 (C, OAc), 170.0 (C, OAc), 170.0 (C, OAc), 169.9 (C, OAc), 160.8 (C=NH), 93.4 (C-1), 68.9 (C-5), 67.40, 67.27, 66.80, 61.2 (C-6), 20.6 (CH 3 , OAc), 20.5 (CH 3 , OAc), 20.5 (CH 3 , OAc), 20.4 (CH 3 , OAc). Scheme S1. Synthesis of GalNHTroc acceptor 10 (similar to the procedure as described for GlcNH 2 ). 35 O AcO OAc AcO AcO O NH CCl 3 24 O HO OH HO TrocHN OTDS 10 O O O HO TrocHN Ph OTDS 23 O AcO OAc AcO TrocHN OTDS O AcO OAc AcO TrocHN O HO OH HO NH 2 22 i) NaHCO 3, H 2 O, TrocCl ii) Ac 2 O,Pyridine i) NH 2 NH 2 ·HOAc, DMF ii) imidazole, TDSCl, DCM NaOMe, MeOH PhCH(OMe) 2 , pTsOH·H 2 O, ACN OAc OH I II III IV V O HO O O AcHN O HO OH O OH O HO OH O HO O O OH HO OH O O OH HO OH O HO OH HO HO AcHN COOH O HO OH HO HO AcHN COOH OH VI VII